The popular and heavily used UO-14 FM satellite has quit working, and some in the amateur satellite community worry that the venerable easy-sat could be down for the count. UO-14 (145.975 MHz up, 435.070 MHz down for Mode J) failed to appear on August 5 over the western Americas, but ground controller Chris Jackson, G7UPN, later was able to reset the satellite from the UK.
The reason for that shutdown remains a mystery. “Since the flight computer is not operating, we have no way of knowing why this event occurred and can only hope that it is not a sign of more problems to come,” Jackson said at the time. His words turned prophetic a week or so later when UO-14 again failed. It was still not back in operation at week’s end.
“It seems that there is a problem with the UO-14 power system–possibly a battery cell has a fault,” Jackson said after the second shutdown. “This is causing the spacecraft to shut down during some eclipses.” Jackson said since this was shutting down the whole spacecraft, it was impossible to implement an automatic routine to periodically cycle the transmitter and keep it on.
Jackson said UO-14 had been changed over to a secondary power system that does not shut down quite as easily, and he was running UO-14’s downlink in telemetry mode to find clues to the problem on board. One possible fix was to make the satellite automatically switch its power back on each time it passes over its Surrey, England, control point.
“UO-14 is getting on toward 14 years and has completed something on the order of 74,000 charge/discharge cycles of its NiCd batteries–not bad really,” Jackson said. “Let’s hope it can manage a few more.”
AMSAT-NA Vice President for User Services Bruce Paige, KK5DO–a regular satellite user–says many UO-14 users have migrated to another FM satellite, SaudiSat SO-50 (145.800 MHz up, 436.800 MHz down, 67 Hz CTCSS tone, for Mode J). “It is a bit more difficult to work as you have to have a 67-Hz PL tone,” he said. “The polarity of the satellite changes many times during a pass.” Paige notes that hams nonetheless have had success with handheld transceivers and very modest antennas. He said SO-50 is typically on over North America.–AMSAT News Service/AMSAT BB